Before you give your handset to repair shop or buy new handset, please try the following procedure to repair your device. First charge your battery more then 70%, If your handset dead or bricked then charge your battery with battery charger or any external charger. Backup your important data if possible like phone-book, message, email, images, settings, EFS, NV, and full nand backup, and in most cases take out SIM card and SD card. After firmware update, format or root your device not possible to recover your data, so online backup is always important. For all of your data, a backup should be done on a external device, hard drive, raid system media or SD card. Remember do anything like firmware update, root, install custom firmware, stock firmware at your own risk we don't take any responsibility of damage your device.